THE EFFECT OF STIMULUS PATTERN, COLOR COMBINATION AND FLICKER FREQUENCY ON STEADY-STATE VISUAL EVOKED POTENTIALS TOPOGRAPHY

We investigated color/luminance characteristics and flicker frequency characteristics from steady-state visual evoked potentials (SSVEPs) topography on sinusoidal patterns and square wave patterns using black-and-white flicker stimulus and isoluminant color combination stimulus. Flicker frequencies of 6-18 Hz to black-and-white flicker stimuli and isoluminant color combination stimuli (red/blue, red/green) were adopted. Each of the stimuli and stimulus patterns were sinusoidal and square wave patterns. The study subjects were 20 healthy, young adult males (9 for monochrome and 11 for colors). Their topographical characteristics were evaluated by the maximum amplitude, central point coordinates, and the ratio of the activated area from the VEP averaged waveform in each recorded area. No significant difference in any of the characteristic parameters between stimulus patterns existed. The isoluminant color combination stimuli had a significantly smaller maximum amplitude compared with the black-and-white flicker stimulus; the central point coordinates and the ratio of the activated area changed considerably. Significant changes in characteristic parameters were also seen between stimulus frequencies. It is suggested that the position and distribution of the neuronal population in the active primary visual cortex differ according to color, luminance, and flicker frequency. However, it is considered that even if the stimulus patterns are different, the active primary visual cortex neuronal population does not change.